 /*
 * $Id: VarStack.java,v 1.1 2004/04/21 10:54:41 eed3si9n Exp $
 * 
 * $Copyright: copyright (c) 2004, e.e d3si9n $
 * $License: 
 * This source code is part of DoubleType.
 * DoubleType is a graphical typeface designer.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This Program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * In addition, as a special exception, e.e d3si9n gives permission to
 * link the code of this program with any Java Platform that is available
 * to public with free of charge, including but not limited to
 * Sun Microsystem's JAVA(TM) 2 RUNTIME ENVIRONMENT (J2RE),
 * and distribute linked combinations including the two.
 * You must obey the GNU General Public License in all respects for all 
 * of the code used other than Java Platform. If you modify this file, 
 * you may extend this exception to your version of the file, but you are not
 * obligated to do so. If you do not wish to do so, delete this exception
 * statement from your version.
 * $
 */
 
package org.doubletype.ossa.module;

import java.util.*;

/**
 * @author e.e
 */
public class VarStack {
	private static VarStack s_varstack = null;
	
	public static VarStack getSingletonInstance() {
		if (s_varstack == null)
			s_varstack = new VarStack();
			
		return s_varstack;
	}
	
	// --------------------------------------------------------------
	
	private ArrayList<VarStackFrame> m_stack = new ArrayList<>();
	
	// --------------------------------------------------------------
	
	public void push(VarStackFrame a_frame) {
		a_frame.beforePush();
		m_stack.add(a_frame);
	}
	
	public VarStackFrame pop() {
		VarStackFrame retval = peek();
		if (retval == null) {
			return retval;
		} // if
		
		m_stack.remove(retval);
		
		return retval;
	}
	
	public VarStackFrame peek() {		
		if (m_stack.size() <= 0) {
			return null;
		} // if
		
		return (VarStackFrame) m_stack.get(m_stack.size() - 1);
	}
	
	public void clear() {
		m_stack.clear();
	}
	
	public int size() {
		return m_stack.size();
	}
	
	/**
	 * goes through the var stack and returns the variable value
	 * @param a_name name of the variable
	 * @return the value of the variable
	 */
	public double get(String a_name) {
		int i;
		double retval = 0.0;
		
		for (i = 0; i < m_stack.size(); i++) {
			VarStackFrame frame 
				= (VarStackFrame) m_stack.get(m_stack.size() - i - 1);
			if (!frame.hasVariable(a_name)) {
				continue;
			} // if
			
			return frame.getValue(a_name);
		} // for i
		
		return retval;
	}
}
